"Polymer concrete", as used herein, is a composite material formed by polymerizing a liquid monomer in admixture with an aggregate. The polymerized liquid monomer serves as a binder for the aggregate. The liquid monomer typically contains one or more monomers and polymerization additives, i.e., catalysts. Additionally, the liquid monomer may include cross-linking agents, coupling agents, initiators, solvents, dissipators, surfactants, accelerators and viscosity control compounds. Polymer concrete materials are prepared from substantially anhydrous compositions.
Polymer concretes are to be distinguished from polymer-impregnated concrete and polymer-portland cement concrete. Polymer-impregnated concrete is a precast portland cement concrete subsequently impregnated with a monomer that is polymerized in situ. Polymer-portland cement concrete is a premixed material in which either a monomer or a polymer is added to a fresh concrete mixture in a liquid, powder or dispersed phase and subsequently polymerized, if needed, and cured.
Polymer concrete compositions, polymer-impregnated concrete, and polymer portland cement concrete are reviewed in Chemical, Polymer and Fiber Additives for Low Maintenance Highways, edited by G. C. Hoff et al. Chemical Technology Review No. 130, Noyes Data Corporation, Park Ridge, N.J., 1979 and Chemical Materials for Constructions, Phillip Maslow, Structures Publishing Company, Farmington, Mich., 1979. Representative patents regarding polymer concrete materials are U.S. Pat. Nos. 4,500,679 to Fontana et al. and 4,460,625 to Emmons et al.
Generally, a composition for preparing a polymer concrete is a substantially non-aqueous slurry of an aggregate component, a monomer binder component and a polymerization catalyst. These components may be packaged separately and mixed on-site to avoid premature polymerization. Monomers used as binders include, but are not limited to, methyl methacrylate and styrene used singly or in admixture and, at times, with other monofunctional monomers or with polyfunctional monomers such as trimethylolpropane trimethacrylate. Polyester-styrene, furan, vinyl ester and epoxy resins and oligomers have also been used in preparing polymer concretes, in each case in combination with suitable catalysts for initiating and/or accelerating the curing of the compositions.
In conventional polymer concretes, the monomer binder component typically cures and sets rapidly. Additionally, the monomer binder component also generally exhibits shrinkage along with a consequent dewetting of the substrate to which the polymer concrete is applied. The methods of the present invention provide polymer concretes that exhibit improved substrate adhesion while maintaining the rapid set times of the conventional polymer concrete.